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Conflicting dimensions on customer print

#1
I am looking for some help with Customer related issue. I have a part drawing with a dimension for a hole. The part is a stamped metal part. The dimension is called out as a range, not a plus-minus tolerance on the drawing. There is a supplementary specification which does include a nominal plus-minus dimension for the hole as well as an overall burr tolerance. We use a simple go/ no-go gauge to inspect the whole on the manufacturing floor. We received a complaint from our customer for a burr present in the hole. The burr was undetected because the part passed our inspection with our go/ no-go pin gauge. I am at a loss at how to ensure we effectively check the part while still using pin gauges. The print calls out for the whole to be (dimensions in inches) .050-.060 diameter. The supplemental specification states nominal is .055 +/-.005 and a burr tolerance of 10% of material thickness. The material is .020 in. thick, which gives me a burr tolerance of .002. We also have to account for plating, which is .0005 in. thick. Can anyone help me out? What size pin gages would be sufficient to ensure the hole meets both size and burr requirements.

**EDIT: For clarification. The burr protrudes up into the hole. not off the face of the part. I have uploaded a picture so you can see.
 

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Ninja

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#2
Others on here are more experienced than I in machining and stamping, but it's Friday afternoon so I figured I'd chime in...

I'm not sure trying to measure a burr (Z-axis) with a pin gage (XY axes) is a great idea.
I can picture a simple burr gage with a 0.002" groove that slides (or doesn't) over the hole as a go-nogo...but a search online did not show me a burr gage.

I would suggest that if you have two specs on the hole, you measure each directly...even if go/nogo for both.

FWIW, from what you've stated, I do not see "conflicting dimensions"... .050-.060 is equal to .055 +/- .005...though others may disagree...
 
#4
Unless you do something afterwords, you're not going to have a burr "inside" the hole. You'll have it on the opposite side of the punch direction. You can check that with an indicator. If you do push it back into the hole, it becomes part of the diameter, imo. So use your pin gage and then check the burr itself with an indicator.
 
#6
Unless you do something afterwords, you're not going to have a burr "inside" the hole. You'll have it on the opposite side of the punch direction. You can check that with an indicator. If you do push it back into the hole, it becomes part of the diameter, imo. So use your pin gage and then check the burr itself with an indicator.
Yes, the burr is on the opposite side of the punch direction on the edge of the material in the hole location. It is very small and very thin put does protrude up into the hole.
 
#7
Others on here are more experienced than I in machining and stamping, but it's Friday afternoon so I figured I'd chime in...

I'm not sure trying to measure a burr (Z-axis) with a pin gage (XY axes) is a great idea.
I can picture a simple burr gage with a 0.002" groove that slides (or doesn't) over the hole as a go-nogo...but a search online did not show me a burr gage.

I would suggest that if you have two specs on the hole, you measure each directly...even if go/nogo for both.

FWIW, from what you've stated, I do not see "conflicting dimensions"... .050-.060 is equal to .055 +/- .005...though others may disagree...
I only say conflicting dimensions because the burr protrudes into the hole yet the hole size still reads ok when checked with the current go gage.
 
#8
Yes, the burr is on the opposite side of the punch direction on the edge of the material in the hole location. It is very small and very thin put does protrude up into the hole.
No it doesn't. Stamped holes have shear and break and essentially 2 diameters. If you gage goes thru I say you're good. If there is a big burr on the outside then you need to tumble/sand it off.
 

Emmyd

Involved In Discussions
#9
We've run into similar situations on stampings - have been rejected with the exact same verbiage. What we found when we were checking with the gage pins was that if the pin went in at an angle, the burr would pass. If the gage pin was inserted at exactly 90 degrees to the flat face, it would not go in. That is how our customer was placing the parts on to pins in their assembly. So, we had to change our gaging instructions to reflect the check the customer was doing on their line.
 
#10
I only say conflicting dimensions because the burr protrudes into the hole yet the hole size still reads ok when checked with the current go gage.
From the picture, that burr has been smashed back into the hole by a subsequent operation. That will close up your dia. If the hole is withing the .050-060 spec, including the burr, then I think you're good to go.
 
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